about 4% of the food america imports comes from japan. including processed fruits and vegetables, cookies, teas, chewing gum and seafood such as scallops, tuna, lobster, shrimp and salmon. if i'm an american consumer, and i'm deciding to sit down for some japanese tuna for dinner. can i feel comfortable that that's been screened, coming through the ports of the u.s.? >> if that japanese tuna had arrived within the last few days or weeks since those tragic events in japan, chances are that it has been screened for radiation. >> reporter: diane, this little device is the powerful radiation detector that's being used. and so far, not one has detected harmful radiation coming in from japan. diane? >> all right, dr. richard besser reporting from the airport with his machine tonight. >>> and still ahead on "world news," complaints, more and more of them, about aggressive, even abusive debt collectors. we tell you a simple step you can do to make them stop calling forever. >>> and what kate middleton has decided to borrow from princess diana's f